Just to close this thread: DTS has confirmed the mentioned behavior and there is no solution. Currently, system-wide default UTIs are given priority - a different approach might be to prefer UTIs defined by installed apps. A bug report is required to request an architectural change - how likely this might be. I won't pursuit further as I've filed a very similar request a decade ago regarding macOS...
Topic:
App & System Services
SubTopic:
Core OS
Tags: